Glass melting furnaces are refractory lined vessels shaped as containers for melting and holding glass. In the melting operation, the incoming glass making materials are heated to about 2800° F. (1550° C.). The glass-making materials usually include a mixture of cullet and batch materials. Cullet is crushed glass from the manufacturing process. Batch materials include sand (silica), lime (limestone or calcium carbonate reduced to calcium monoxide), soda ash (sodium monoxide), and sometimes other materials such as feldspar, salt cake, and metal oxides. During the melting operation, the cullet melts first to increase the heat transfer to the batch materials and to reduce the melting time.
Glass melting furnaces include pot furnaces, glass tanks, tank furnaces, and the like. Glass may be constructed of separate refractory brick or blocks within a frame. The blocks fit together without mortar and typically are arranged in a rectangular shape to hold molten glass. The mechanical pressure from the frame and outer blocks holds the blocks together. The refractory blocks usually receive considerable wear from the molten glass and the charging of glass making materials. Molten glass is highly corrosive. The refractory blocks usually are made of composite clays having alumina, zirconia, and silica (AZS). The AZS refractory blocks are made from molten material cast into molds, which are machined after hardening. The refractory blocks can become deeply scored and may develop wear spots or portions where the molten glass has eroded or dissolved the refractory. The wear spots typically grow until the refractory fails to hold the molten glass. The wear spots shorten the service life of glass tanks and often are unpredictable, thus disrupting production of molten glass.
Brass furnaces are refractory lined vessels shaped as containers for melting brass. Brass scrap is collected and transported to the foundry where it is melted in the furnace and recast into billets. The furnace is also used to heat up billets extruded the brass into the right form and size. In the melting operation, the incoming brass-making materials are heated to about 2000° F. (1100° C.).